According to a Konkuk University study, “The transgenerational inheritance of autism-like phenotypes in mice exposed to valproic acid during pregnancy,” conducted by researchers Chang Soon Choi et al.[1]:

The findings of this study present a new perspective in autism spectrum disorder susceptibility and heritability where autism can be inherited in subsequent generations after a pathologic environmental exposure in the first generation.

A well-known environmental risk factor of autism spectrum disorder in humans is the ValProic Acid, an anti-epileptic drug. ValProic Acid-exposed animals have become one of the most widely used models of autism spectrum disorder for its clinical relevance.

Autism-like behavioral phenotypes found in the first generation of ValProic Acid-exposed offspring persisted to the second generation and third generation. The frontal cortices of the first generation and third generation showed some imbalanced expressions of excitatory/inhibitory synaptic markers, suggesting a transgenerational epigenetic inheritance.

These results open the idea that excitatory/inhibitory imbalance and autism spectrum disorder-like behavioral changes induced by environmental insults in mice can be epigenetically transmitted, at least, to the third generation.